The invention relates to an apparatus and Corresponding method for compressing still images which is compatible with a JPEG (Joint Photographic Experts Group) Still Image Compression Standard.
When high-quality images must be compressed to save memory or transmission requirements, it is common practice to first transmute the images to another space where the information can be represented more compactly. This is usually done block-by-block with a linear transformation (matrix multiplication); a typical arrangement is to perform 8-point transforms on row segments of 8 pixels and then to perform 8-point transforms on the 8-element column segments of this row-transformed image. Equivalently a single 64-point transform can be performed on a pixel block of 64 pixels arranged in an 8-by-8 block. A good choice for a one dimensional transform is the discrete Chebychev transform: ##EQU1##
There are several advantages of this transform including a) the compression is near-optimal by some measures, b) there are fast computational algorithms for performing this transform and its inverse, and c) deblurring (enhancement of the initial image) can be readily performed in the transform space, given certain assumptions described in Reference [1].